Caprica is a pre-quel to Battlestar Galactica.
One needn't have been a fan of the original series to follow Caprica, but the series depicts life on a planet by the same name, prior to it being destroyed by the Cylons.
The show focuses on two families, the Graystones and the Adamas. They each are forced to deal a troubling breakthrough in artificial intelligence, one that brings about unforeseen consequences. Caprica is set 50 years prior to the events of Battlestar Galactica.